Toy balloons are made from natural rubber. Only natural rubber has the strength, very high elongation at break, and other properties needed for the toy balloon. A major problem with these balloons has been that when they are inflated, they slowly discolor and go from a shiny, bright color to a flat, dull color within a few hours or days. Natural rubber is very susceptible to oxidation caused by reaction with the small amount of ozone in the air and by reaction with oxygen catalyzed by ultraviolet radiation in sunlight. The reactions proceed much faster when the rubber is strained, such as when the balloon is inflated. Oxidation is retarded in the uninflated balloon through the addition of small amounts of wax which bloom to the surface of the rubber and form a protective coating. However, when the balloon is inflated, this wax coating breaks and exposes the surface of the balloon to oxidation. Oxidation occurs much more rapidly in hot weather, or in outside locations where ultraviolet radiation from sunlight is greater.
This oxidation reaction causes the formation of microscopic cracks on the surface of the balloon which scatter light and make the balloons change in appearance. Balloons that are initially clear gradually turn to an opaque, dull, white color on oxidation and are no longer transparent. Oxidation turns colored balloons from a bright, shiny color to a dull, flat color.
In recent years, inflated clear balloons have become popular containers for stuffed animals, toys, and a wide variety of other merchandise and gifts. Articles are placed inside large, inflated clear balloons which resemble giant bubbles. This has been made possible through the development of the balloon stuffer machine, a device which holds a balloon open by applying a vacuum to the outside of it. This allows large items to be placed inside the balloon. Many stores and retailers have come to use balloons as "wrapping" for gifts in order to sell the merchandise that goes inside the balloon.
When the clear balloon oxidizes, it becomes cloudy or opaque, and it is no longer possible to see the merchandise inside. Therefore, the value of the balloon as a gift wrapper becomes very diminished. Also, this problem of oxidation makes it impossible for retailers to make up stuffed balloons in advance since the balloons will turn opaque and will no longer be marketable. Another problem is that the return rate is high when people who purchase clear balloons with items inside become dissatisfied when the balloons lose their transparency in a short period of time and the merchandise inside can no longer be seen.
In addition to balloons stuffed with merchandise, many air and helium filled balloons used as decorations suffer from deteriorating appearance and appeal because of the formation of a layer of surface oxidation. This is especially true for large balloon decorations or balloon sculptures which must remain in place for several days, such as in shopping centers. A much greater market for balloon decorations would be possible if the balloons could be made to keep their bright, shiny appearance for several days.
Retailers have attempted to solve this problem of balloons becoming opaque due to oxidation in a number of ways; however, none of these solutions are completely satisfactory. One solution involves coating the inflated balloon with spray furniture wax and then buffing it to remove excess wax. Other materials used to coat inflated balloons in attempts to retard oxidative opacification are silicone oils, light petroleum oils, hair spray containing lacquer, and clear acrylic spray. However, these materials have a number of problems. They are difficult and time consuming to apply, and many of them cause the balloons to burst or deflate in highly oxidizing conditions such as hot weather or sunlight. Furthermore, they are expensive to use, and at best they retard opacification of the balloon for only a few days or less under typical conditions. Another disadvantage is that the wax and oil coatings smudge easily when handled leaving unsightly fingerprints on the balloon.
Another method used to retard oxidative opacification of balloons is to coat the inflated balloon with an aqueous solution of polyvinyl alcohol. Although this prevents opacification for an extended period of time, it has the disadvantage of being very time consuming and messy to apply. This requires a large area to hang the inflated balloons to drip and dry, and drying takes at least 30 minutes. Therefore, this method cannot be used at the point of sale if space is limited such as a kiosk in a shopping mall. Furthermore, it has been found that latex balloons with an outside coating of polyvinyl alcohol have a tendency to deflate or burst in hot weather if they are not kept in an air conditioned environment. This greatly limits the usefulness of balloons coated with polyvinyl alcohol.
It is known to make large size (3 foot and larger inflated diameter) meteorological balloons used to carry weather instruments aloft from neoprene synthetic rubber since it has better physical properties than natural rubber at the low temperature of high altitude. U.S. Pat. No. 3,415,767 relates to plasticizers for neoprene meteorological balloons to further improve low temperature properties at high altitude. U.S. Pat. No. 3,626,052 discloses making meteorological balloons having improved low temperature properties from a polyisoprene-neoprene film containing compatible plasticizers. U.S. Pat. No. 2,646,370 discloses a method of increasing the freeze resistance of neoprene film after it has been cured.
U.S. Pat. No. 3,475,201 discloses improving the ozone resistance and tensile strength of neoprene meteorological balloons by coating them with a cured composition composed of a filler such as carbon black and an elastomeric polymer of an alkylene oxide or alpha-olefins.
U.S. Pat. No. 2,929,110 relates to manufacture of a streamlined meteorological balloon by forming two spherical neoprene balloons, coating one end of each balloon with natural rubber latex, drying the coating, then joining the two balloons together at the coated ends, and subsequently heat curing the entire assembly while the balloons are held in the joined position.
U.S. Pat. No. 3,062,696 relates to pneumatic tires having improved resistance to groove cracking by coating the unvulcanized tire tread with a neoprene cement and subsequently co-curing the coating and fire.
U.S. Pat. Nos. 3,411,982 and 3,286,011 relate to elastomer articles such as gloves and girdles having an improved "slip coating" to aid the wearer in donning and removing. The slip coating is a blend of an elastomer and an alkyl acrylate resin. Neoprene is disclosed as an elastomer component of the slip finish. The coated article is a natural or synthetic rubber latex dipped film. This patent does not disclose or suggest to use neoprene coating on balloons.
U.S. Pat. No. 2,941,257 relates to a coating of chloroprene (neoprene) over latex in producing rubber gloves which are more resistant to the action of oils and detergents.
None of these patents provide any insight into avoiding the opacification or clouding of transparent balloons. Certainly transparency is not a concern with any of the articles discussed in these references.